We report on a high-precision, real-time photon beam localization and characterization instrument. The device uses a 2-D (image) sensor coupled to a hardware image processing system. The system uses two different algorithms that both run in parallel on field programmable gate array logic using data from a single active pixel array sensor. The first algorithm mimics the ubiquitous quadrant photodiode design that features high precision but has limited range and requires calibration cycles. The second algorithm calculates the location of the center of gravity. We compare the merits of both methods by measuring the displacement of a light beam. It is shown that the center of gravity (or centroid) method offers the advantage of large dynamic range with excellent linearity. By the method of operating on identical image data captured from these experiments, we aim to investigate both algorithms and compare their performance.